One widely used method of artificial lift in the production of hydrocarbon fluids, such as crude oil, is characterized by the provision of a submersible electric motor-driven multistage pump which is disposed in the well and submerged in the fluid entering the wellbore for pumping the fluid to the surface through an elongated tubing string connected to the pump. It is conventional practice in such artificial lift installations to extend the electrical power cable to the pump trained generally alongside the production tubing string and strapped directly to the tubing for support of the cable and to minimize entanglement of the cable with structural features of the well.
However, a disadvantage of such arrangements is realized particularly in instances where the fluid, such as crude oil, being pumped through the tubing string is relatively hot. The electrical power cable may suffer thermal degradation from sustained exposure to high temperatures as a result of heat transfer from the tubing string directly to the cable or through its protective sheath. Moreover, elevated operating temperatures of the cable may also reduce its efficiency of electrical power transmission.
Depending on the characteristics of the reservoir being pumped the temperature of the oil flowing through the production tubing string to the surface may be in the range of 150.degree. F. to 350.degree. F., for example. Moreover, the heat generated by the pump electric motor and by the pump itself may raise the temperature of the oil flowing through the tubing string substantially higher than ambient well temperature conditions. Accordingly, for the first two or three hundred feet of tubing string extending uphole from the pump itself, heat transferred from the oil in the tubing string to the power cable may be substantial. Thus, it is desirable to provide for minimizing heat transferred to the power cable from the production tubing string while at the same time providing effective support of the cable by the tubing string.
An important consideration in providing for support of the power cable for submersible pump-type well installations is the ease with which the cable can be secured to the tubing string as the tubing string is being made up and lowered into the well. The complex and hazardous activities involved in making up elongated well tubing strings, including work associated with installing a submersible pump, strongly favors simplifying and minimizing the effort of any task related to such installations. Accordingly, the present invention has been developed with these desiderata in mind and with a view to providing a unique insulated support for electrical power cable for submersible well pump installations which is easy to install and which may utilize a method of installation which minimizes the activity required in advantageously securing the power cable to the well tubing string.